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Triethylamine (TEA) is an effective medium for inhibiting dye aggregation and improving the luminescence of dye-sensitized lanthanide-doped upconversion nanoparticles (UCNPs). However, excessive TEA will cause quenching of upconversion luminescence. In this paper, the possible mechanism of TEA affecting upconversion luminescence is discussed. It is found that TEA can enhance the nucleophilicity of the solvent, leading to dye shedding from the nanoparticles. Reducing the dielectric constant of the solvent can make TEA play a more positive role in upconversion luminescence and photostability of dye-sensitized UCNPs. When heptanol is selected as the solvent for CyBSO-sensitized β-NaYF4:20%Yb3+,2%Er3+ (UNs), TEA can increase the upconversion luminescence by 6.0 times relative to that in methanol. More importantly, the optimal content of TEA in heptanol is 3700 times more than that in methanol. Under the action of large amounts of TEA in heptanol, a novel upconversion nanoprobe for detecting ascorbic acid is developed with a limit of detection of 0.103 μM and high selectivity over potential interfering species. Meanwhile, the high concentration of TEA in heptanol can improve the photostability of CyBSO-sensitized UNs by 10.4 times, which is of paramount importance for the practical application of dye-sensitized UCNPs. [ABSTRACT FROM AUTHOR]

Although dye sensitization is an effective strategy to improve the upconversion luminescence of lanthanide-doped upconversion nanoparticles (UCNPs), the sensitization effect is limited due to the high probability of dye aggregation. To address the problem, the tetraphenylethene group is introduced into cyanine dye, which not only inhibits the tight packing of cyanine dyes on the UCNP surface but also increases the fluorescence quantum yield. As a result, a 135-fold enhancement of upconversion luminescence in dye-sensitized UCNPs is achieved compared to that in non-sensitized UCNPs under excitation at 785 nm with the power density of 5 W cm−2. Moreover, a facile method is found that triethylamine (TEA) can further increase the upconversion luminescence by 7 times. Spectral properties of cyanine dyes on the UCNP surface and in the aggregated state suggest that TEA can also suppress the close packing of cyanine dyes. We speculate that the inhibitory effect of TEA originates from the electrostatic control effect. Furthermore, the highly efficient upconversion nanoparticles has been successfully used in security printing. [ABSTRACT FROM AUTHOR]

Two Ru(II) phenanthroline complexes (Ru‐ph and Ru‐py) were synthesized and their photophysical properties were systematically investigated. For Ru‐py, the conjugation of pyrene at 3‐ and 8‐positions of auxiliary ligand 1,10‐phenanthroline can increase the phosphorescence quantum yield, prolong the triplet lifetime and reduce the triplet energy level. The extended triplet lifetime of Ru‐py was revealed by using the density function theory calculations, which is originated from the triplet state equilibrium between the metal‐to‐ligand charge‐transfer (3MLCT) state and the intraligand (3IL) state. The upconversion fluorescence of 2‐substituted anthracene derivatives (DTACl, DTACN and DNACN) sensitized by Ru‐ph and Ru‐py in DMF was investigated under monochromatic 488 nm excitation with an ultralow power density of 40 mW/cm2. Among them, Ru‐py/DTACl presents the highest upconversion quantum yield (7.4 %). It is found that a small energy gap between the triplet states of sensitizer and emitter helps to increase upconversion quantum yield besides the high triplet‐triplet annihilation efficiency and fluorescence radiation of emitter and the long triplet lifetime of sensitizer. [ABSTRACT FROM AUTHOR]

A new multi-functional crystal has been implemented by combining the acousto-optic (A/O) modulation with Raman laser output, which has never reported before. Notably, the $\alpha $ -BTM displaying an adequate A/O figure of merit of $10.18\times 10^{-18}\,\,\text{s}^{3}$ /g using the comparison method is originally tailored to fabricate an A/O modulator that exhibits a high diffraction angle and diffraction efficiency of 1.432° and 82.1% at 1064 nm, respectively, which can be competitive with that of TeO2. Pumped by a pulsed laser, sequentially, the self-Q-switch Raman laser working at 1178.1 nm is successfully realized based on $\alpha $ -BTM crystal. A maximum output power of 86 mW operating at 1178.1 nm and the repetition frequency of 15 kHz were obtained with the pump power of 27 W. Our works not only enrich the family of A/O materials, but also opens up a viable route towards exploiting the design of multi-functional crystal. [ABSTRACT FROM AUTHOR]

Two sandwich‐type porphyrin complexes Pd(MeTPP)2 and Pt(MeTPP)2 have been synthesized by the longitudinal coordination of metal ion and porphyrin. The sandwich‐type porphyrin complexes present long triplet lifetime, which is almost 1.4 times longer than the single‐decker porphyrin complexes. Their long triplet lifetimes result in high upconversion quantum yields. An increasing upconversion quantum yield (ΦUC) of up to 29.1 % is obtained under excitation of low power density at 78 mW cm−2. Moreover, porphyrin complexes are used in photoelectrochemical cell to realize sub‐bandgap photo capture and conversion. It is manifested that sandwich‐type structure provides an effective method for porphyrin complexes to enhance the upconversion quantum yield. [ABSTRACT FROM AUTHOR]

A high-performance Schottky diode based on a 600- ${\mu }\text{m}$ -thick Cr-doped ${\beta }$ -Ga2O3 single crystal has been fabricated using SnOx as the Schottky contact. The SnOx film was deposited in argon/oxygen mixture gas to ensure an oxygen-rich stoichiometry in Ga2O3 near the Schottky interface, thus reducing oxygen deficiency-related interface state density. The SnOx film included three components: Sn, SnO, and SnO2, as revealed by X-ray photoelectron spectroscopy characterization. The high-quality Ga2O3 single crystal grown by an edge-defined film-fed method has a carrier concentration of $1.0 \times 10^{18}$ cm $^{-3}$ and an electron mobility of ~90 cm2/Vs. The current density–voltage characteristics of the Schottky diode demonstrated high performance with a large barrier height of 1.19 eV, a close-to-unity ideality factor of 1.02, and a high rectification ratio beyond $10^{10}$. The frequency-dependent capacitance and conductance analysis revealed that the maximum active interface state density is $2.46 \times 10^{12}$ eV $^{-1}$ cm $^{-2}$ at a frequency of 500 kHz. [ABSTRACT FROM AUTHOR]

A series of new fused‐heterocycle phenanthrene derivatives, namely 9‐(o‐benzofuryl)phenanthrene (Compd. 1), 9,10‐bis(o‐benzofuryl)phenanthrene (Compd. 2), 9‐(o‐dibenzofuryl)phenanthrene (Compd. 3) and 9‐(o‐benzothienyl)phenanthrene (Compd. 4) were designed and synthesized in an effort to obtain aggregation‐induced emission enhancement (AIEE) of ultraviolet (UV) light. The results have shown that Compd. 1 and 2 possess the AIEE of UV‐blue light while Compd. 3 presents UV‐AIEE characteristic. However, Compd. 4 is AIEE‐inactive due to sulfur's heavy atom effect. Based on the absorption and fluorescence in both solution and aggregation, it was found that there is no direct correlation of the intramolecular change‐transfer (ICT) and AIEE properties. Associated with the single‐crystal analyses, it was confirmed that the twisted molecular configuration leading to rigid stacking arrangement with larger intermolecular distance is not immediately relevent to AIEE intensity. It was the degree of the restricted intramolecular rotation (DRIR) in the aggregation that shows direct proportional to the AIEE intensity, in the order of Compd. 1 (5.4‐fold increase) > Compd. 3 (3.2‐fold increase) > Compd. 2 (2.6‐fold increase). UV electroluminescence (EL) from organic light‐emitting diode (OLED) consisting of Compd. 3 as emitting layer was firstly reported. The ultraviolet AIEE (UV‐AIEE) is firstly reported based on the newly synthesized fused‐heterocycle phenanthrene derivatives. The degree of the restricted intramolecular rotation (DRIR) of the aggregate is directly proportional to the AIEE intensity. And the ultraviolet electroluminescence (UV‐EL) fabricated by Compd. 3 as emitting layer is first reported. [ABSTRACT FROM AUTHOR]

Single crystal perovskite materials with the intriguing properties of wide optical absorption range, low trap density, photoluminescence, and superior charge-transfer have emerged as a new class of revolutionary photovoltaic semiconductors promising for various applications. A technique to realize microstructures or microdevices on the surface of single crystal can facilitate the incorporation of these materials into optoelectronic applications. Here, we first reported the fabrication of 1-D mciropores, microlines, and 2-D micropatterns such as word “USTC,” number “2016” and “Olympic rings” on the surface of CH3NH3 PbI3 single crystal by femtosecond laser ablating. The effect of parameters such as exposure time, laser peak intensity, and scanning speed was quantitatively investigated to determine the parameter intervals capable of ensuring the required resolution. By fabricating periodic grating microstructures, the perovskite surfaces showed bright iridescence from dark blue to red due to the grating diffraction effect. Moreover, it is found that the fluorescence peak strength of processed area obviously grows with laser peak intensity and scanning speed, which is attributed to the increasing surface roughness caused by higher laser peak intensity and slower scanning speed. These works are beneficial for researchers to better understand the intrinsic property of single crystal perovskite and accelerate perovskite-based optoelectronics applications. [ABSTRACT FROM PUBLISHER]

Two new ternary copper-containing arsenides, Sr2Cu3As3 and Eu2Cu3As3, were synthesized through Pb-flux reactions. In combination with theoretical calculations, the crystal structures of these compounds were determined through single-crystal X-ray diffraction. Both compounds crystallize in the orthorhombic space group Cmcm (no.63) with the cell parameters a = 4.2465(6)/4.1866(5) Å, b = 17.604(3)/17.486(2) Å, and c = 4.2552(6)/4.2096(5) Å for the Sr- and Eu-containing compounds, respectively. Temperature-dependent magnetic susceptibility measurements suggest that both ferromagnetic and antiferromagnetic coupling exists in the structure of Eu2Cu3As3 for the Eu 4f states. According to DFT calculations, these compounds are metallic, and the Cu 3d orbitals make significant contributions to the states around the Fermi level. [ABSTRACT FROM AUTHOR]

Three new donor–π bridge–acceptor (D–π–A) compounds based on triphenylamine-propenone, namely 4-(1-phenylprop-2-en-1-one-3-yl)triphenylamine (PhO-TPA), 4-(1-(pyridin-2-yl)prop-2-en-1-one-3-yl)triphenylamine (PyO-TPA) and 4,4′,4′′-(tri(1-(pyridin-2-yl)prop-2-en-1-one-3-yl))triphenylamine (TPyO-TPA), were synthesized through an aldol addition reaction. Their intramolecular charge transfer (ICT) and aggregation emission properties as well as packing structures were investigated. All of them show solvent polarity dependent emission. The density function theory calculations reveal that the ICT characteristic of the HOMO–LUMO transition is responsible for the large solvent effect. In aggregates, PhO-TPA and PyO-TPA exhibit aggregation-induced enhanced emission (AIEE). However, TPyO-TPA displays a different fluorescence behavior. Single-crystal analyses of PhO-TPA and PyO-TPA show that the weak intermolecular interactions and the suppression of the ICT state result in the efficient AIEE. The understanding on the AIEE fluorophores together with ICT characteristic will help to develop materials with color tenability, especially the ones with efficient emission in solid states. [ABSTRACT FROM AUTHOR]

Two new quaternary pnictide-based multinary compounds, Ba4AgGa5P8 and Ba4AgGa5As8, were synthesized from Pb-flux reactions. By using the single crystal X-ray diffraction technique the structures were determined to crystallize with the noncentrosymmetric (NCS) space group Iba2 (No. 45) (cell parameters: a = 7.294(9)/7.4769(8) Å, b = 18.03(2)/18.5766(19) Å, c = 6.557(8)/6.7590(7) Å for the P- and As-containing compounds, respectively). Theoretical calculations indicate strong SHG responses for both compounds, which are approximately two times larger than that of AgGaSe2. Based on the calculated cutoff-energy-dependent static SHG coefficients, the large NLO coefficients of these compounds should originate from the distorted GaPn4 tetrahedra, which construct various layers and chains giving rise to a large polarization. Both compounds have moderate birefringence (Δn), 0.157 and 0.206 for Ba4AgGa5P8 and Ba4AgGa5As8, respectively, suitable to meet the phase-matching condition in the SHG process. [ABSTRACT FROM AUTHOR]

A series of new multinary phosphide Zintl compounds, Ba5Ga2GeSnP8, Ba5Al2GeSnP8, Ba5Ga6GeP12, and Ba5Ga6SnP12, have been synthesized through high-temperature Pb or Sn flux reactions. The structures of the compounds, which have been determined by single-crystal X-ray diffraction, feature two different new structural types bearing various polyanion chain fragments. Ba5 Tr2GeSnP8 ( Tr = Al, Ga) crystallize in the monoclinic C2/ m (No. 12) space group with cell parameters: a = 16.8211(10)/16.7586(21) Å, b = 6.0115(4)/6.0867(8) Å, c = 9.5873(6)/9.5983(12) Å, β = 111.9270(10)/112.1880(10)° for the Al- and Ga-containing compounds, respectively. For Ba5Ga6 TtP12 ( Tt = Ge, Sn), the compounds belong to a different orthorhombic system [space group: Cmcm (No. 63)] with the cell dimensions: a = 10.5222(6)/10.5802(9) Å, b = 16.2717(10)/16.3529(14) Å, c = 13.9093(8)/13.9643(12) Å for Ba5Ga6GeP12 and Ba5Ga6SnP12. Despite the clear differences in the crystallographic parameters, these two types of structures are closely related through the [ Tr2P4] and [ Tr5P12] polyanion chains ( Tr = triels) as well as the significant mixing between the triel and tetrel atoms. The close relationships between these phases and some previously reported analogues are also discussed in detail. Theoretical calculations based on DFT methods confirm the precise electron nature of these compounds, which are also consistent with results from crystallographic data and the optical absorption measurements. [ABSTRACT FROM AUTHOR]

Two easily-prepared pyridine-based derivatives of (Z)-2-(4-amino-phenyl)-3-(pyridine-4-yl)acrylonitrile (I) and (Z)-2-phenyl-3-(pyridin-4-yl)acrylonitrile (II ) were designed, synthesised and characterised. Due to the formation of a complex with Hg2+, hence leading to an enhanced ICT effect, I exhibits a visible colour change from light yellow to orange, rendering it suitable for use as a naked-eye sensor for rapid detection of Hg2+ in an aqueous ethanol solution. When mixed with Hg2+, I interacts with Hg2+ in a 2 : 1 (Y1-Hg2+) stoichiometry via a coordination bond with an association constant of 7.7 × 108 M-2 (R2 = 0.96). The present probe I exhibits excellent reproducibility, reversibility, sensitivity and selectivity with the presence of low concentration of Hg2+ (1.74 × 10-10 M). [ABSTRACT FROM AUTHOR]

Two new europium-containing Zintl phases, Eu3Si2As4 and Eu3Ge2As4, were discovered from metal flux reactions and their structures were identified by using single-crystal X-ray diffraction. Both compounds crystallize in the monoclinic space group P21/ c and are isotypic to Sr3Ge2As4. Magnetic property studies were performed and the results proved the long-range antiferromagnetic behavior for Eu3Ge2As4 but with a positive Weiss constant, which suggested the coexistence of both ferromagnetic and antiferromagnetic order of Eu 4f electrons in the structure. Density functional calculations were incorporated to understand the related magnetic properties as well. [ABSTRACT FROM AUTHOR]

Four new quaternary chalcogenides, Ba4AgGaS6 ( 1), Ba4AgGaSe6 ( 2), Ba4CuInS6 ( 3), and Ba4AgInS6 ( 4), were synthesized by solid-state reactions and their structures were characterized through single-crystal X-ray diffraction. In spite of their similar chemical compositions, the flexible arrangement between the transition metals and the triel atoms leads to subtle differences in their polyanion structures. All structures feature similar [MTrQ6]8− 1D polyanionic chains (M=Cu, Ag; Tr=Ga, In; Q=S, Se), which are constructed from corner-sharing MQ4 or TrQ4 tetrahedra. However, the transition metals and triels are mixed in 1, 2, and 3, but they occupy independent crystallographic sites in 4. As a result, compounds 1- 3 belong to the known Ba2CoS3 ( Pnma No. 62) or Ba2MnS3 ( Pnma No. 62) class, whereas 4 crystallizes in its own structural type within the monoclinic P21/ c (No. 14) space group. The structural relationship among these new phases was also studied with the aid of DFT calculations and related optical properties are presented as well. [ABSTRACT FROM AUTHOR]

Luminogenic materials with AIE (aggregation-induced emission) and AIEE (aggregation-induced enhanced emission) characteristics have attracted substantial research interest due to their potential applications in optics, electronics environmental and the biological sciences. Here, we successfully synthesized two novel indolo[3,2-b]carbazole derivatives (compounds 3 and 4) with strong symmetrical groups, which were demonstrated to exhibit superior AIEE properties. Both 3 and 4 contain the same π-conjugated core structure, but slightly differ in the cyano-substituted stilbene group, giving rise to a high charge mobility, similar optical properties and energy band-gaps. The bulky cyano group attached to a vinylene moiety generates intramolecular co-planarity and prevents π–π stacking, whereby the emission in the aggregates can be enhanced. In addition, it is found that the cyano group also plays an important role in the formation of J-type aggregation, which is advantageous to the appearance of AIE and/or AIEE properties. A slight modification of the terminal substituent group renders compounds 3 and 4 AIEE properties entirely. As revealed by crystallographic data, the multiple intermolecular hydrogen bonding in 4 restricts intramolecular vibration and rotation, which enables 4 to emit intensely in the solid state. Moreover, cyano groups endow 3 with an improved self-assembly ability under the proper conditions. The molecules of 3 self-organize into one-dimensional ordered microfibers and/or nanorods that show a significant optical waveguide with different water fractions, indicating that the aqueous suspension of microfibers favors fluorescence emission. Our results demonstrate that the AIEE properties of the novel indolo[3,2-b]carbazole derivatives are highly related to the molecular structure and aggregate packing. [ABSTRACT FROM AUTHOR]

Two new Zintl compounds A10LaCdSb9 (A=Ca, Yb), namely, Ca9.81(1)La0.97(1)Cd1.23(1)Sb9 and Yb9.78(1)La0.97(1)Cd1.24(1)Sb9, have been designed and synthesized by applying the Zintl concept. Although both compounds are isoelectronic with their Ca11InSb9 and Yb11InSb9 analogues, they crystallize in a new structure type with the orthorhombic space group Ibam (No.72) and feature very complex anion structures, which are composed of unique [Cd2Sb6]12− clusters, dumbbell-shaped [Sb2]4− dimers, and isolated [Sb]3− anions. For Yb9.78(1)La0.97(1)Cd1.24(1)Sb9, an extremely low lattice thermal conductivity of 0.29 W m−1 K−1 was observed at 875 K, which almost approaches the lowest reported limit of nonglassy or nonionically conducting bulk materials. According to thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses, both compounds show very good thermal stability and no melting or phase transition processes were found below 1173 K. Although related thermoelectric property studies on Yb9.78(1)La0.97(1)Cd1.24(1)Sb9 only present a maximum ZT of 0.11 at 920 K, owing to its low Seebeck coefficients, these materials are still very promising for their high temperature stability and low thermal conductivity. Furthermore, as mixed cations exist with different charges, it makes this system very flexible in tuning the related electrical properties. [ABSTRACT FROM AUTHOR]

Four new D–π–D (or D–π–D–π–D) complexes 9-ethyl-3-E-((1-ferrocenyl)vinyl)-carbazole (1), 9-ethyl-3,6-E,E-((1,1-diferrocenyl)vinyl)- carbazole(2), 10-ethyl-3-E-((1-ferrocenyl)vinyl)-phenothiazine (3), 10-ethyl- 3,7-E,E- ((1,1-diferrocenyl)vinyl)-phenothiazine (4), have been obtained by solid-phase Wittig reactions and fully characterized. The four complexes were treated with iodine leading to four corresponding [D–π–A]+I3−ferrocenium triiodides 1+I3−(5), 2+I3−(6), 3+I3−(7) and 4+I3−(8), respectively. The results of single crystal X-ray diffraction analysis show that 1and 2display better coplanarity between the Fc and carbazole subunits than that between the phenothiazine and ferrocene moieties, which leads to a better π-electron delocalization. Both the poor π-electron in [D–π–A]+ferroceniums and the heavy iodine atom have a negative effect on the electrochemical properties. The complexes 1–8undergo multi-step redox processes and show lower oxidation potentials compared with those of ferrocene. Density functional theory (DFT) calculations are performed and the experimental redox properties of the complexes are studied. The eight complexes show MLCT and π–π* transitions in the UV-visible range in solution, which have been verified by TD-DFT theoretical calculations. In all cases the highest-lying occupied molecular orbitals of the eight complexes are mainly localized on the Fe dorbitals and show a greater Fe proportion than that of alkyl in the complexes, whereas the LUMOs and LUMO+1 are mainly from the π orbitals of the conjugated vinyl carbazole or phenothiazine unit. [ABSTRACT FROM AUTHOR]

Demonstrates the luminescence of dye-doped polymer films induced by corona discharge. Color of emissions.

A type of luminescence was observed from fluorescent dye-doped polymer films by corona discharge excitation. The polymer film was deposited on a transparent electrode, and direct current corona discharge was caused in argon atmosphere using this electrode as the anode. Emission of three elemental colors, i.e., red, green, and blue, were obtained from polyvinilcarbazole films doped with 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran, 3-(2′-Benzothiazolyl)7-diethylaminocoumarin, and 1,1,4,4-tetraphenyl-1,3-butadiene, respectively. The drive current required for the luminance of 10 cd/m2 was as low as 100 μA/cm2 and the maximum quantum efficiency was 9.95 cd/A, which is nearly four orders of magnitude higher than that of the common injection type electroluminescent cells with the same material. The origin of this high efficiency can be attributed to the efficient hole blocking by the gas phase and also by concurrent effects of different luminescence processes including electroluminescence by charge recombination, photoluminescence by ultraviolet excitation, and cathodoluminescence by electron impact excitation. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]